Dr. Gizmo.

Low Temp Not Cool For Engine

November 13, 1994|By Phil Arendt.

Q-When my 1993 Toyota pickup overheated at 40,000 miles, I replaced the thermostat and flushed the cooling system. Recently, the engine has been running too cool. I wouldn't be too concerned about this, but the condition seems to be hurting engine performance. What's the problem? T.B., West Covina, Calif.

A-You aren't imagining a change. An engine running below operating temperature may not function properly. Computer controls in the emission control system rely on proper engine temperature. If the engine doesn't reach that temperature, the emission controls and fuel management system reduce engine performance. It's possible that the thermostat doesn't meet carmaker temperature specifications or it's defective. Make sure the correct thermostat is in the cooling system. Also, test the coolant temperature sensor. Often, the sensor is damaged when an engine overheats. If the sensor is faulty, replace it.

Q-After 30 minutes of travel, the headlight switch in my 1981 Chevrolet gets very hot. I don't like to have the lights on for long periods for fear of melting the plastic bezel or starting a fire. I took the car to two mechanics who say they never had this problem before. They tell me that before a fire would start, the fuse will blow. I would rather have the problem fixed instead of relying on a fuse blowing. Is a new headlight switch needed? M.G., Baltimore

A-I've never measured the temperature of the headlight switch knob metal shaft, but it's normal for it to get hot enough to surprise the heck out of you when you touch it. Headlights with rocker switches get just as hot, but the heat is shielded from the operator. A vehicle operator is most likely to find that the shaft on a conventional push-pull switch is hot, hot, hot after 30 minutes or so. I have not come across a car where a normally operating switch has melted the plastic escutcheon or bezel. Also, I have not found a normal switch to cause a fire. Incidentally, the headlight system switch has built-in circuit protection that might prevent a fire if the safeguard works. Also, it's not likely that you will find a fuse in the fuse panel that will kill the circuit if the wiring short circuits.

Q-Recently, I took my 1993 Dodge Stealth to a dealership for a 22,500-mile service and oil change. After the service, I drove the vehicle for two days and parked it in the garage for the weekend. Monday morning, I started the engine and heard a loud knocking sound. I shut the engine off and had the car towed back to the dealer. I was told that the engine needed new lifters. A technician replaced the lifters under the factory warranty. Is this normal? Should I expect more problems? D.M., Wheeling

A-Lifter ticking sounds after prolonged parking periods are normal in the Stealth. It is unusual for lifters to make loud knocking sounds that require replacement so soon. I suspect that the vehicle hasn't received proper regular maintenance or whoever changed the engine oil didn't do a proper job. If either scenario is true, future problems may develop. Perform regular maintenance according to the service schedule listed in your owner's information.

Q-I'm 80 years old. I drive my 1984 Buick Riviera mostly in Park Ridge, where the speed limit is 35 miles per hour. Occasionally I'll drive down Irving Park Road, where I can get going 50 miles per hour. Should I place the transmission in overdrive for all my driving? M.B., Chicago

A-Place the shift lever in overdrive for all your driving needs. The automatic transmission will shift into overdrive when needed and disengage overdrive when it's not needed.

Q-The engine in my 1984 Chevrolet Celebrity is difficult to start and makes a loud screech when I turn the ignition key. I took the car to a mechanic who asked me to leave the car overnight. The next morning he adjusted the choke and heard the screeching. He told me that the engine flywheel needed replacement. The estimated cost was $450. I authorized the repair. After the work, the engine is still difficult to start and the screech is still there. Did the mechanic take advantage of me? E.A., Elmhurst

A-He took your money and the car isn't fixed, but he probably hasn't taken advantage of you. Return to the shop and explain the trouble. It's possible that the new flywheel is faulty or he failed to install a new starter when he replaced the flywheel. That should be investigated. As for the starting problem, he needs to do more testing when the engine is cold. So your car is due for another overnight stay at the shop.

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Phil Arendt is an automotive technical consultant for the AAA-Chicago Motor Club. Readers may send technical questions about cars and trucks to him at Dr. Gizmo, A+Automotive Career Counselors Inc., P.O. Box 548, Cary, Ill. 60013 or to his America Online mailbox DRGIZMO.